As described in the Wikipedia at en.wikipedia.org/wiki/Immunoassay: the Wikipedia text quoted herein is released under CC-BY-SA, see creativecommons.orelicenses/by-sa/3.0.                “An immunoassay test is a biochemical test that measures the concentration of a substance in a biological liquid, typically serum or urine, using the reaction of an antibody or antibodies to its antigen. The assay takes advantage of the specific binding of an antibody to its antigen. Monoclonal antibodies are often used as they only usually bind to one site of a particular molecule, and therefore provide a more specific and accurate test, which is less easily confused by the presence of other molecules. The antibodies picked must have a high affinity for the antigen (if there is antigen available, a very high proportion of it must bind to the antibody).        Both the presence of antigen or antibodies can be measured. For instance, when seeking to detect the presence of an infection the concentration of antibody specific to that particular pathogen is measured. For measuring hormones such as insulin, the insulin acts as the antigen.        For numerical results, the response of the fluid being measured must be compared to standards of a known concentration. This is usually done though the plotting of a standard curve on a graph, the position of the curve at response of the unknown is then examined, and so the quantity of the unknown found.        Detecting the quantity of antibody or antigen can be achieved by a variety of methods. One of the most common is to label either the antigen or antibody. The label may consist of an enzyme, enzyme immunoassay (EIA)), radioisotopes such as I-125 Radioimmunoassay (RIA), magnetic labels (magnetic immunoassay—MIA) or fluorescence. Other techniques include agglutination, nephelometry, turbidimetry and Western Blot. A number of these do form a directly visible line or test output but require an instrument to measure or capture the test output.        Immunoassays can be divided into those that involve labelled reagents and those which involve non-labelled reagents. Those which involve labelled reagents are divided into homogenous and heterogeneous (which require an extra step to remove unbound antibody or antigen from the site, usually using a solid phase reagent) immunoassays. Heterogeneous immunoassays can be competitive or non-competitive.                    In a competitive immunoassay, the antigen in the unknown sample competes with labelled antigen to bind with antibodies. The amount of labelled antigen bound to the antibody site is then measured. In this method, the response will be inversely proportional to the concentration of antigen in the unknown. This is because the greater the response, the less antigen in the unknown was available to compete with the labelled antigen.            In non-competitive immunoassays, also referred to as the “sandwich assay,” antigen in the unknown is bound to the antibody site, and then labelled antibody is bound to the antigen. The amount of labelled antibody on the site is then measured. Unlike the competitive method, the results of the non-competitive method will be directly proportional to the concentration of the antigen. This is because labelled antibody will not bind if the antigen is not present in the unknown sample.                        Because homogeneous assays do not require this step, they are typically faster and easier to perform.”        
As described in the Wikipedia at en.wikipedia.org/wiki/Lateral flow test:                “Lateral flow tests also known as Lateral Flow Immunochromatographic Assays are a simple device intended to detect the presence (or absence) of a target analyte in sample (matrix). Most commonly these tests are used for medical diagnostics either for home testing, point of care testing, or laboratory use. Often produced in a dipstick format, Lateral flow tests are a form of immunoassay in which the test sample flows along a solid substrate via capillary action. After the sample is applied to the test it encounters a coloured reagent which mixes with the sample and transits the substrate encountering lines or zones which have been pre-treated with an antibody or antigen. Depending upon the analytes present in the sample the coloured reagent can become bound at the test line or zone. Lateral Flow Tests can operate as either competitive or sandwich assays.        In principle any coloured particle can be used, however most tests commonly use either latex (blue colour) or nanometer sized particles of gold (red colour). The gold particles are red in colour due to localized surface Plasmon resonance. Fluorescent or magnetic labelled particles can also be used—however these require the use of an electronic reader to access the test result.        The sample first encounters coloured particles which are labelled with antibodies raised to the target analyte. The test line will also contain antibodies to the same target, although it may bind to a different epitope on the analyte.        The test line will show as a coloured band in positive samples.        The sample first encounters coloured particles which are labelled with the target analyte or an analogue. The test line contains antibodies to the target/its analogue. Unlabelled analyte in the sample will block the binding sites on the antibodies preventing uptake of the coloured particles.        The test line will show as a coloured band in negative samples.        Most tests are intended to operate on a purely qualitative basis. However it is possible to measure the intensity of the test line to determine the quantity of analyte in the sample. Implementing a Magnetic immunoassay (MIA) in the lateral flow test form also allows for getting a quantified result.        While not strictly necessary, most tests will incorporate a second line which contains an antibody that picks up free latex/gold in order to confirm the test has operated correctly.        Time to obtain the test result is a key driver for these products. Tests can take as little as a few minutes to develop. Generally there is a trade-off between time and sensitivity—so more sensitive tests may take longer to develop. The other key advantage of this format of test compared to other immunoassays is the simplicity of the test—typically requiring little or no sample or reagent preparation.        Probably the most well known examples of lateral flow tests are home pregnancy tests. However rapid tests or point of care tests are available for a wide range of applications including: HIV tests, Troponin T, test Malaria tests, drugs of Abuse tests, Fertility tests, Respiratory disease tests etc. Clinical tests can be applied to urine, saliva, blood, or stool samples. Tests are available for both human and animal diagnostics. Tests are also available for non clinical applications including testing food and water for contaminants.”        
FIG. 1 shows a typical lateral flow strip as commonly used in rapid diagnostic applications. The strip contains a sample application pad 102, a conjugate pad 104, a membrane (typically nitrocellulose) 106 along which an analyte flows, and a waste absorbing pad 108. These components are bonded by an adhesive layer 110 onto a carrier strip 112, usually constructed from plastic sheet.
Immobilised on the membrane 106 are one or more test line(s) 114 containing capture antigens or antibodies for the target(s) of interest, and a control line 116 containing a control capture antigen or antibody. The test line(s) 114 also include visible or coloured or fluorescent labels so that the test result is displayed in the form of visible or otherwise optically detectable lines of the test and control lines 114, 116.
The lateral flow strip described above and shown in FIG. 1 may also be contained in a plastic cassette having an opening for sample introduction and an open “window” for viewing the test and control lines 114, 116.
Currently, such lateral flow strips and other similar types of biomedical test strips are widely used to diagnose a wide variety of medical conditions, including pregnancy, health markers, and infectious diseases, including flu, for example.
Nucleic Acid Amplification
The amplification of nucleic acids is important in many fields, including medical, biomedical, environmental, veterinary and food safety testing. In general, nucleic acids are amplified by one of two methods: polymerase chain reaction (PCR) or isothermal amplification, both of which are described below.
Polymerase Chain Reaction (PCR)
As described in the Wikipedia at en.wikipedia.org/wiki/Polymerase chain reaction: the Wikipedia text quoted herein is released under CC-BY-SA, see creativecommons.org/licenses/by-sa/3.0.                “The polymerase chain reaction (PCR) is a scientific technique in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence.        Developed in 1983 by Kary Mullis, PCR is now a common and often indispensable technique used in medical and biological research labs for a variety of applications. These include DNA cloning for sequencing, DNA-based phylogeny, or functional analysis of genes; the diagnosis of hereditary diseases; the identification of genetic fingerprints (used in forensic sciences and paternity testing); and the detection and diagnosis of infectious diseases. In 1993, Mullis was awarded the Nobel Prize in Chemistry along with Michael Smith for his work on PCR.        The method relies on thermal cycling, consisting of cycles of repeated heating and cooling of the reaction for DNA melting and enzymatic replication of the DNA. Primers (short DNA fragments) containing sequences complementary to the target region along with a DNA polymerase (after which the method is named) are key components to enable selective and repeated amplification. As PCR progresses, the DNA generated is itself used as a template for replication, setting in motion a chain reaction in which the DNA template is exponentially amplified. PCR can be extensively modified to perform a wide array of genetic manipulations.        Almost all PCR applications employ a heat-stable DNA polymerase, such as Taq polymerase, an enzyme originally isolated from the bacterium Thermus aquaticus. This DNA polymerase enzymatically assembles a new DNA strand from DNA building-blocks, the nucleotides, by using single-stranded DNA as a template and DNA oligonucleotides (also called DNA primers), which are required for initiation of DNA synthesis. The vast majority of PCR methods use thermal cycling, i.e., alternately heating and cooling the PCR sample to a defined series of temperature steps. These thermal cycling steps are necessary first to physically separate the two strands in a DNA double helix at a high temperature in a process called DNA melting. At a lower temperature, each strand is then used as the template in DNA synthesis by the DNA polymerase to selectively amplify the target DNA. The selectivity of PCR results from the use of primers that are complementary to the DNA region targeted for amplification under specific thermal cycling conditions.PCR Principles and Procedure        PCR is used to amplify a specific region of a DNA strand (the DNA target). Most PCR methods typically amplify DNA fragments of up to ˜10 kilo base pairs (kb), although some techniques allow for amplification of fragments up to 40 kb in size.        A basic PCR set up requires several components and reagents. These components include:                    DNA template that contains the DNA region (target) to be amplified.            Two primers that are complementary to the 3′ (three prime) ends of each of the sense and anti-sense strand of the DNA target.            Taq polymerase or another DNA polymerase with a temperature optimum at around 70° C.            Deoxynucleoside triphosphates (dNTPs; nucleotides containing triphosphate groups), the building-blocks from which the DNA polymerase synthesizes a new DNA strand.            Buffer solution, providing a suitable chemical environment for optimum activity and stability of the DNA polymerase.            Divalent cations, magnesium or manganese ions; generally Mg2+ is used, but Mn2+ can be utilized for PCR-mediated DNA mutagenesis, as higher Mn2+ concentration increases the error rate during DNA synthesis.            Monovalent cation potassium ions.                        The PCR is commonly carried out in a reaction volume of 10-200 μl in small reaction tubes (0.2-0.5 ml volumes) in a thermal cycler. The thermal cycler heats and cools the reaction tubes to achieve the temperatures required at each step of the reaction (see below). Many modern thermal cyclers make use of the Peltier effect, which permits both heating and cooling of the block holding the PCR tubes simply by reversing the electric current. Thin-walled reaction tubes permit favorable thermal conductivity to allow for rapid thermal equilibration. Most thermal cyclers have heated lids to prevent condensation at the top of the reaction tube. Older thermocyclers lacking a heated lid require a layer of oil on top of the reaction mixture or a ball of wax inside the tube.Procedure        Typically, PCR consists of a series of 20-40 repeated temperature changes, called cycles, with each cycle commonly consisting of 2-3 discrete temperature steps, usually three. The cycling is often preceded by a single temperature step (called hold) at a high temperature (>90° C.), and followed by one hold at the end for final product extension or brief storage. The temperatures used and the length of time they are applied in each cycle depend on a variety of parameters. These include the enzyme used for DNA synthesis, the concentration of divalent ions and dNTPs in the reaction, and the melting temperature (Tm) of the primers.                    Initialization step: This step consists of heating the reaction to a temperature of 94-96° C. (or 98° C. if extremely thermostable polymerases are used), which is held for 1-9 minutes. It is only required for DNA polymerases that require heat activation by hot-start PCR.            Denaturation step: This step is the first regular cycling event and consists of heating the reaction to 94-98° C. for 20-30 seconds. It causes DNA melting of the DNA template by disrupting the hydrogen bonds between complementary bases, yielding single-stranded DNA molecules.            Annealing step: The reaction temperature is lowered to 50-65° C. for 20-40 seconds allowing annealing of the primers to the single-stranded DNA template. Typically the annealing temperature is about 3-5 degrees Celsius below the Tm of the primers used. Stable DNA-DNA hydrogen bonds are only formed when the primer sequence very closely matches the template sequence. The polymerase binds to the primer-template hybrid and begins DNA synthesis.            Extension/elongation step: The temperature at this step depends on the DNA polymerase used; Taq polymerase has its optimum activity temperature at 75-80° C., and commonly a temperature of 72° C. is used with this enzyme. At this step the DNA polymerase synthesizes a new DNA strand complementary to the DNA template strand by adding dNTPs that are complementary to the template in 5′ to 3′ direction, condensing the 5′-phosphate group of the dNTPs with the 3′-hydroxyl group at the end of the nascent (extending) DNA strand. The extension time depends both on the DNA polymerase used and on the length of the DNA fragment to be amplified. As a rule-of-thumb, at its optimum temperature, the DNA polymerase will polymerize a thousand bases per minute. Under optimum conditions, i.e., if there are no limitations due to limiting substrates or reagents, at each extension step, the amount of DNA target is doubled, leading to exponential (geometric) amplification of the specific DNA fragment.            Final elongation: This single step is occasionally performed at a temperature of 70-74° C. for 5-15 minutes after the last PCR cycle to ensure that any remaining single-stranded DNA is fully extended.            Final hold: This step at 4-15° C. for an indefinite time may be employed for short-term storage of the reaction.                        To check whether the PCR generated the anticipated DNA fragment (also sometimes referred to as the amplimer or amplicon), agarose gel electrophoresis is employed for size separation of the PCR products. The size(s) of PCR products is determined by comparison with a DNA ladder (a molecular weight marker), which contains DNA fragments of known size, run on the gel alongside the PCR products.PCR Stages        The PCR process can be divided into three stages:        Exponential amplification: At every cycle, the amount of product is doubled (assuming 100% reaction efficiency). The reaction is very sensitive: only minute quantities of DNA need to be present.        Leveling off stage: The reaction slows as the DNA polymerase loses activity and as consumption of reagents such as dNTPs and primers causes them to become limiting.        Plateau: No more product accumulates due to exhaustion of reagents and enzyme.PCR Optimization        In practice, PCR can fail for various reasons, in part due to its sensitivity to contamination causing amplification of spurious DNA products. Because of this, a number of techniques and procedures have been developed for optimizing PCR conditions. Contamination with extraneous DNA is addressed with lab protocols and procedures that separate pre-PCR mixtures from potential DNA contaminants. This usually involves spatial separation of PCR-setup areas from areas for analysis or purification of PCR products, use of disposable plasticware, and thoroughly cleaning the work surface between reaction setups. Primer-design techniques are important in improving PCR product yield and in avoiding the formation of spurious products, and the usage of alternate buffer components or polymerase enzymes can help with amplification of long or otherwise problematic regions of DNA. Addition of reagents, such as formamide, in buffer systems may increase the specificity and yield of PCR.Amplification and Quantification of DNA        Because PCR amplifies the regions of DNA that it targets, PCR can be used to analyze extremely small amounts of sample. This is often critical for forensic analysis, when only a trace amount of DNA is available as evidence. PCR may also be used in the analysis of ancient DNA that is tens of thousands of years old. These PCR-based techniques have been successfully used on animals, such as a forty-thousand-year-old mammoth, and also on human DNA, in applications ranging from the analysis of Egyptian mummies to the identification of a Russian tsar.        Quantitative PCR methods allow the estimation of the amount of a given sequence present in a sample—a technique often applied to quantitatively determine levels of gene expression. Real-time PCR is an established tool for DNA quantification that measures the accumulation of DNA product after each round of PCR amplification.PCR in Diagnosis of Diseases        PCR permits early diagnosis of malignant diseases such as leukemia and lymphomas, which is currently the highest-developed in cancer research and is already being used routinely. (See the studies cited in the EUTOS For CML study article at eutos.org/content/molecular_monitoring/information/pcr_testing/, especially notes 10-13.) PCR assays can be performed directly on genomic DNA samples to detect translocation-specific malignant cells at a sensitivity that is at least 10,000-fold higher than that of other methods.        PCR also permits identification of non-cultivatable or slow-growing microorganisms such as mycobacteria, anaerobic bacteria, or viruses from tissue culture assays and animal models. The basis for PCR diagnostic applications in microbiology is the detection of infectious agents and the discrimination of non-pathogenic from pathogenic strains by virtue of specific genes.        Viral DNA can likewise be detected by PCR. The primers used need to be specific to the targeted sequences in the DNA of a virus, and the PCR can be used for diagnostic analyses or DNA sequencing of the viral genome. The high sensitivity of PCR permits virus detection soon after infection and even before the onset of disease. Such early detection may give physicians a significant lead in treatment. The amount of virus (“viral load”) in a patient can also be quantified by PCR-based DNA quantitation techniques (see below).Isothermal Amplification Methods        
As described in the Wikipedia at en.wikipedia.org/wiki/Variants_of_PCR#Isothermal_amplification_met-hods:                “Some DNA amplification protocols have been developed that may be used alternatively to PCR:                    Helicase-dependent amplification is similar to traditional PCR, but uses a constant temperature rather than cycling through denaturation and annealing/extension steps. DNA Helicase, an enzyme that unwinds DNA, is used in place of thermal denaturation.            PAN-AC also uses isothermal conditions for amplification, and may be used to analyze living cells.                        1. Nicking Enzyme Amplification Reaction referred to as NEAR, is isothermal, replicating DNA at a constant temperature using a polymerase and nicking enzyme.                    Recombinase Polymerase Amplification (RPA). The method uses a recombinase to specifically pair primers with double-stranded DNA on the basis of homology, thus directing DNA synthesis from defined DNA sequences present in the sample. Presence of the target sequence initiates DNA amplification, and no thermal or chemical melting of DNA is required. The reaction progresses rapidly and results in specific DNA amplification from just a few target copies to detectable levels typically within 5-10 minutes. The entire reaction system is stable as a dried formulation and does not need refrigeration. RPA can be used to replace PCR (Polymerase Chain Reaction) in a variety of laboratory applications and users can design their own assays.Detection of the Amplification Products                        
Existing immunoassay tests such as lateral flow tests are often limited by sensitivity, particularly where only small amounts of the target material or antigen such as viral DNA being tested for are present in the sample. DNA amplification has the advantage that it can significantly improve the sensitivity of a test which involves detection of DNA as it provides a huge increase in the presence of the target DNA in the sample under test. However, diagnostic tests based on DNA amplification typically require a complex instrument to perform accurate thermocycling in reasonable times and to instrument the detection stage which may use expensive detection technologies such as fluorescence detection or sensitive bioluminescence detection with devices such as photomultiplier tubes and complex optics. Even where a simple isothermal DNA amplification approach is used, the same complex instrumental detection is typically required.
Performing DNA amplification prior to detection using lateral flow has the advantage that it allows for a simpler test format with a potentially non-instrumented detection using visual inspection of test lines on the lateral flow strip. Even where instrumented detection of the lateral flow strip is desirable for reasons of repeatability, consistency and sensitivity, the instrumentation and sensor required to read a lateral flow strip can be significantly less costly, more compact, and less complex than those required to read chemical or fluorescent beacons or probes directly in the fluid products from DNA amplification.
Using a lateral flow strip test as the detection and display following DNA amplification is an established technique. However, the inventor has identified a number of difficulties or shortcomings of such prior art methods and apparatus. Firstly, they will typically involve a number of manual steps that make the approach susceptible to error, and add time and complexity for the user. In particular, the manual steps required to separate a sample, add it to a DNA amplification mix, provide amplification, decant the amplified product onto a test strip and then flush the strip with a buffer solution—are unsuitable for many applications, including:                (i) simple point of care or field-deployed diagnostic;        (ii) operation by untrained or non-technical users; and        (iii) tests suitable for CLIA waver approval for a diagnostic test in the USA.        
A further difficulty with a manually operated, exposed or partially exposed test process of this diagnostic approach is the risk of release of amplified products into the test environment. The amplified solution can contain millions or billions of amplified DNA material, and/or segments of the target DNA under test. If these are transferred from an amplification chamber to a lateral flow test strip in a way that can leak or contaminate the user or the surrounding work area, then any following tests will be contaminated. Any of the released amplification products that contaminate samples for subsequent tests will themselves be amplified and thereby result in false positive results. Moreover, a work area or room contaminated by amplification products may be very difficult to decontaminate, and will introduce false positive results and uncertainty compromising all further use of the diagnostic test.
It is desired, therefore, to provide a nucleic acid amplification and detection kit, apparatus, and/or method that alleviates one or more difficulties of the prior art, or that at least provides a useful alternative.